title: Acute hormonal responses before and after 2 weeks of HIT in well trained junior triathletes.
abstract: The aim was to compare the acute hormonal response to a single HIT session at the beginning and end of a HIT shock microcycle. 13 male junior triathletes (15.8±1.8 yrs.) performed 16 HIT sessions within a 2 week period. Venous blood samples were collected before and after the first and last HIT session. Significant increases in cortisol (first session +89.7%; last session +70.3%) and hGH (first session +435.1%; last session +314.6%) concentrations were observed after both training sessions (P<0.05). The acute responses of cortisol, hGH, T3, and fT3 were not different between the first and last HIT sessions (P=1.00). Although no acute changes in testosterone were detected after the training sessions, testosterone concentrations were significantly higher at all time points (62.6-80.1%) during the last compared to first training session (P≤0.001). Findings from the present study reveal that 16 sessions of HIT led to significant increases in baseline concentrations of serum testosterone. This might indicate a heightened anabolic state even in junior triathletes. Based on the hormonal data, we conclude that at the end of this 2 week microcycle no familiarization effect was evident and that the training stimulus produced by HIT was still great enough to "stress" the athletes and induce positive training adaptations.
authors.affiliation: Institute of Training Science and Sport Informatics, German Sport University Cologne, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Zinner
authors.affiliation: Institute of Training Science and Sport Informatics, German Sport University Cologne, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Wahl
authors.affiliation: Institute of Training Science and Sport Informatics, German Sport University Cologne, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Achtzehn
authors.affiliation: Minto Prevention and Rehabilitation Centre, University of Ottawa Heart Institute, Ottawa, Canada.
authors.forename: J L
authors.initials: JL
authors.lastname: Reed
authors.affiliation: Institute of Training Science and Sport Informatics, German Sport University Cologne, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Mester
mesh_terms: D000222:Adaptation, Physiological; D000293:Adolescent; D054874:Athletic Performance / Q000502:physiology; D001642:Bicycling / Q000502:physiology; D006728:Hormones / Q000097:blood*; D019382:Human Growth Hormone / Q000097:blood; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D008297:Male; D010101:Oxygen Consumption; D010806:Physical Education and Training / Q000379:methods*; D010807:Physical Endurance / Q000502:physiology*; D012420:Running / Q000502:physiology; D013550:Swimming / Q000502:physiology; D013739:Testosterone / Q000097:blood; D014284:Triiodothyronine / Q000097:blood
chemical_list: D006728:Hormones; D014284:Triiodothyronine; D019382:Human Growth Hormone; D013739:Testosterone; D006854:Hydrocortisone